I’m curious about how to determine the number of layers in complex PCBs like motherboards or graphics cards. I often look at vias and connections to estimate the layer count in simpler PCBs, but I’m unsure how to count layers in more complex boards. Do you have any tips or clues on how to determine the layer count of these advanced PCB designs accurately?
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It depends on the application you’re working on. For most embedded applicaitons, you can get away with 4 or 6 layers.
However, if you’re design involves DDR memories, high pin count BGAs etc… you may want to plan this ahead and decide layer count accordingly.
Also layer stackup is super important from EMI/EMC perspective as well.
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It’s not clear to me if you’re asking how to tell how many layers there are in a finished board, or if you’re asking how to predict how many layers will be needed. To try to find out how many layers were used in a finished board can be very easy or very difficult. Often holding it up to a bright light is enough. And if the designer used layer markers it’s easy. Otherwise you almost always have to section it. Sometimes just cutting a little groove near the edge is enough. X–rays can help to. As far as predicting the required layers the are lots of algorithms on the net, especially ones designed around dense BGA’s. Siierra has one on our website. Check it out at www.protoexpress.com